import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        Set<String> set = new HashSet<>(wordDict);

        int n = s.length();
        boolean[] dp = new boolean[n+1];
        dp[0] = true;
        s = ' ' + s;

        for (int i = 1; i <= n; i++) {
            for (int j = i; j >= 1; j--) {
                if(dp[j-1] && set.contains(s.substring(j,i+1))){
                    dp[i] = true;
                    break;
                }
            }
        }

        return dp[n];
    }
}
